regexclojure

clojure regex named groups


I have a problem with re-find in clojure. Actually I'm doing

(re-find #"-(?<foo>\d+)-(?<bar>\d+)-(?<toto>\d+)-\w{1,4}$" 
"http://www.bar.com/f-a-c-a-a3-spok-ser-2-phse-2-1-6-ti-105-cv-9-31289-824-gu" )

My result is fine:

["-9-31289-824-gt" "9" "31289" "824"]

But I would prefer to have a hash looking like:

{:foo "9" :bar "31289" :toto "824"}

I have understood that java.util.regex.Matcher/group is doing something like that but I haven't been able to use it correctly. Thanks for your help


Solution

  • JDK didn't support named capture groups until JDK 7.

    Here's announcement on oracle blog

    Quote:

    This convenient feature has been missed in Java RegEx for years, now it finally got itself in JDK7 b50.

    Since clojure supports JDK >= 6 you're out of luck if you're looking for something native (clojure uses java regex Patterns and Matchers behind the scenes).

    You can always use external libraries, like named-re. That one gives you exactly what you need.

    Calling

    (require 'named-re.core)
    (re-find #"-(?<foo>\d+)-(?<bar>\d+)-(?<toto>\d+)-\w{1,4}$" 
         "http://www.bar.com/f-a-c-a-a3-spok-ser-2-phse-2-1-6-ti-105-cv-9-31289-824-gu" )
    

    will return

    {:toto "824", :bar "31289", :foo "9", :0 "-9-31289-824-gu"}